Recently, inexpensive and pervasive networking technologies based on various small devices are emerging or being commercialized. People can make good use of various home appliances such as refrigerators, TVs, washing machines, PCs, and audio equipments once such appliances are connected to a home network. For the purpose of such home networking, UPnP™ (hereinafter, it is referred to as UPnP for short) specifications have been proposed.
A UPnP network consists of a plurality of UPnP devices, services, and control points. A service on a UPnP network represents a smallest control unit on the network, which is modeled by state variables. A CP (Control Point) on a UPnP network represents a control application equipped with functions for detecting and controlling other devices and/or services. A CP can be operated on an arbitrary device which is a physical device such as a PDA providing a user with a convenient interface. A CP can also constitute a single device together with another service, e.g., a renderer service which expresses images by rendering media data. Therefore, multiple CPs can exist on a UPnP network and the user can control operations on a desired service by choosing a convenient CP depending on his/her current location or employed device.
Once a home network as above is built in a particular place such as a home, the user can conveniently make use of desired operations (e.g., operations of duplicating or transferring data between separate devices) irrespective of his/her current location; moreover, multiple users can share the same device at the same time, in the same place.
As described above, when multiple users use networked devices simultaneously or sequentially, or multiple tasks are carried out on networked devices simultaneously or sequentially, required quantity of data transmission may exceed transmission bandwidth provided by a network. In this case, network access for data transmission should be restricted.
For example, when additional network access is requested and bandwidth required by the request cannot be provided by a current network while multiple content data are being streamed through the network, either the request is rejected or a current streaming connection is released when the priority of the request for additional access is higher than that of a part of the current streaming connections. In this case, a user watching streaming content confronts abrupt suspension.